This incident doesn't have anything to do with race.

It's just a mob mentality. Most people tend to be very protective of small children, so when people in this mob saw someone injuring a small child, violence erupted. When a child is injured, emotions get out of control and all reasoning goes out the window, regardless of your race.

And usually when a mob starts to get violent, there are very few people brave enough to try to put a stop to it for fear of getting hurt themselves.